1. Field of the Invention
The present invention relates to an endoscopic ligation tool and endoscope for ligating a varix that has formed in an internal body tissue, such as the esophagus or stomach.
2. Description of the Related Art
An esophageal varix ligation technique may be used alone or in combination with endoscopic sclerotherapy, in which a sclerosing agent is injected, as a method for treating a varix that has formed in the esophagus or stomach. In this esophageal varix ligation technique, suction is employed to draw the varix toward a cylindrical endoscopic ligation tool attached to the end of the endoscope, and a pre-attached O-ring is released and suspended around the root of the varix. The varix is then mechanically ligated under the elastic force of the O-ring, and thereby obliterated. As an example of this endoscopic ligation tool, a device has been proposed in which an O-ring disposed to the front end of an inner cylinder is disconnected by means of injecting a liquid between the inner and outer cylinders, as disclosed in FIG. 1 of Japanese Patent Publication No. 2958219.
A design has also been proposed as disclosed in FIG. 1 of the Specification of U.S. Pat. No. 4,735,194, or FIG. 2 of Published Japanese translation No. 2002-526194 of International Publication, for example, in which a O-ring is caught on a wire which is inserted into the channel of the endoscope, and the O-ring is then disconnected from the end of the cylindrically shaped member by pulling out the wire.
However, the endoscopic ligation tool according to the first reference (Japanese Patent No. 2958219) is problematic in that it requires the attachment of a supply device and tube along the inserted part of the endoscope for supplying liquid to the endoscopic ligation tool, and the preparations for this are troublesome. Further, in both the endoscopic ligation tool according to the second reference (U.S. Pat. No. 4,735,194) and third reference (Published Japanese translation No. 2002-526194 of International Publication), it is necessary to pass the wire though the channel, so that, in the case where concurrently performing endoscopic sclerotherapy, it is not possible to pass the necessary injection syringe, etc. through the channel. In addition, the devices disclosed in the second and third references are also problematic in that the assembly operations therefore are complicated.
In addition, while the endoscopic ligation tools disclosed in the first and second reference documents do require removal of the endoscope from the body cavity after use, they do not require considerable preparation provided that just the O-ring, or just the inner cylinder with the attached O-ring, can be exchanged. The endoscopic ligation tool according to the third reference is problematic, however, in that once all the O-rings have been used, it is necessary to start all the preparation operations over from the beginning.
The present invention was conceived in view of the above-described circumstances, and has as its objective the provision of an endoscopic ligation tool and endoscope capable of ligating an internal body tissue that has a simple design that does not require a wire or a device for supplying a liquid, this endoscopic ligation tool and endoscope making the aforementioned procedure easier and less time consuming.